1. Field of the Invention
The present invention relates to an optical disk apparatus for reproducing record information through irradiating a light-beam upon a disc-like information recording medium, which is called by an “optical disk”, and in particular, relates to an optical disk apparatus for achieving stable read-out operation even to a multi-layered disk having plural numbers of recording layers, which are piled in the direction of a rotation axis of the disk, and a focus-jumping control method thereof.
2. Description of the Related Art
A disc-like information recording medium called by the “optical disk” and an optical disk apparatus being able to record/reproduce onto/from such the information recording medium, due to the characteristics of being non-contact in the operation, large in storage capacity, and enabling high-speed access, and further of being a replaceable and cheap medium, they are applied widely to be various kinds of recording/reproducing apparatuses; such as, a recording/reproducing apparatus for digital audio signal and/or digital video signal, for example, and further an external recording medium for a computer, etc.
On the other hand, with an optical disk, being the optical information recording medium to be used within such the apparatus, since it is remarkable in increasing of the storage capacity thereof, and then in addition to the disk of construction of a single layer of the conventional art, there are further proposed and put into practical use of various kinds of multi-layered optical disks, each of which forms the information recording layers in plural numbers thereof in the direction of the rotation axis thereof. As an example of such the multi-layered optical disks, for example, an optical disk of DVD two (2) layers for exclusive use of read-out, which is called by “DVD-DL (Dual layer)”, has the plural number of layers, i.e., a layer “0” and a layer “1”, on all of both the information recording layers are recorded with addresses in advance; therefore, for the optical disk apparatus side of reproducing those, even if shifting (i.e., focus-jumping) between those plural numbers of layers at any position on the radial direction of the disk, it is possible to confirm or identify the address on that layer.
For that reason, conventionally, within the disk drive (i.e., the optical disk apparatus) for exclusive use of read-out, normally, an operation of seeking to an address position of a target is conducted after conduction of the focus-jumping at the present address position, when conducting a seek control including the focus-jumping operation between those plural numbers of the recording layers.
Also other than those, such as, in Japanese Patent-Laying Open No. 2000-251271 (2000), for example, it is already known that, within a disk drive apparatus for recording or reproducing data onto/from the signal recording surfaces having the structure of plural numbers of layers, the focus-jumping is executed at a disk radial position corresponding to the address position near to an inner periphery side when conducting access between the separate signal recording surfaces (or, layers), for the purpose of reducing ill influence from swing or oscillation of the surface.
Further, for example, in Japanese Patent-Laying Open No. 2002-304750 (2002) is also disclosed an optical disk apparatus, for achieving both the focus-jumping to the target layer and the seeking to the target address, at the same time, correctively. However, in this patent document, observations are made upon an amount of shifting into the radial direction and a speed of shifting speed during the time-period of the focus-jumping, correctly, through an interpolation of a track-cross signal during the time-period of the focus-jumping that cannot be measured, which is executed at the same time of the seeking operation; thereby, achieving the correct seeking to the objected address with high speed and high performance.